bullet: Update to version 2.82 (bullet revision 2705)
    
Remove patch that has been applied upstream.

Fixes several bugs.


git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk@60918 954f8c5b-7b00-dc11-b283-0030488c597c
rigidbody: Use bullet's own fixed constraint

Should be no functional changes.

git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk@60919 954f8c5b-7b00-dc11-b283-0030488c597c